Infrared detection and control device

ABSTRACT

An electronic detection and control device comprising a first electronic circuit means having its input connected to an electrical source, the output of said first electronic circuit means connected to at least one radiation-emitting semiconductor device, said first electronic circuit means adapted to provide electrical energy to said semiconductor device to excite said semiconductor device to produce a radiated signal, said radiated signal defining a radiation screen, a radiation-sensing semiconductor device whose input is adapted to receive said radiated signal, the output of said radiation-sensing semiconductor device connected to a second circuit means, said second circuit means adapted to provide an output signal responsive to the presence or absence of any obstruction in said electronic screen, or responsive to the presence or absence of any ambient radiated energy received by said radiation-sensing semiconductor device.

United States Patent 1 Zeldman et al.

[ 51 Mar. 27, 1973 [54] INFRARED DETECTION AND CONTROL DEVICE [75}Inventors: Maurice l. Zeldman; Edward J. Walker; Suresh K. Gupta, all ofPittsburgh, Pa.

[7 3] Assignee: North America Rockwell Corporation, Pittsburgh, Pa.

[22] Filed: May 18, 1971 [2]] App]. No.: 144,518

[52] U.S. Cl ..250/83.3 ll, 250/2l7 SS, 250/221 [51] Int. Cl. ..G0lj1/00 [58] Field of Search ..250/83.3 H, 211 J, 217 SS, 250/221 [56]References Cited UNITED STATES PATENTS 3,534,35l 10/1970 Hamden, Jr. eta1. ..250/221 X 3,551,682 l2/l970 Kerhoas et al ..250I2l7 SS X 3,652,8593/1972 Toussaint ..250I2l7 SS X Primary Examiner-Archie R. BorcheltAttorney-John R. Bronaugh, Floyd S. Le'vison, E. Dennis OConnor andRichard A. Speer [57] ABSTRACT An electronic detection and controldevice comprising a first electronic circuit means having its inputconnected to an electrical source, the output of said first electroniccircuit means connected to at least one radiation-emitting semiconductordevice, said first electronic circuit means adapted to provideelectrical energy to said semiconductor device to excite saidsemiconductor device to produce a radiated signal, said radiated signaldefining a radiation screen, a radiation-sensing semiconductor devicewhose input is adapted to receive said radiated signal, the output ofsaid radiation-sensing semiconductor device connected to a secondcircuit means, said second circuit means adapted to provide an outputsignal responsive to the presence or absence of any obstruction in saidelectronic screen, or responsive to the presence or absence of anyambient radiated energyreceived by said radiation-sensing semiconductordevice.

6 Claims, 4 Drawing Figures Alternating Current Source D.C. ControlPower supply To All Electronic Circuits 28 54 32 38 POW,r Clock 1st.Oscil. cwck 7 Pulse Coincidence Stretch Detection Filter 40 42 44 46 5O52 34 I I l 2 Photo Steering Obstr. -v--T"--:- Detector 0" 7 Pulse *36 EArray Means Stretch Radiating J Diode Ambient 2nd. JZ; Pulse CoincidenceStretcher Detection 5e so so mama M27 1915 3, 723, 737

sum-130m INVENT Maurice I. dmun,

Edwdrd J. Walker 8 Suresh K. Gupta 1 INFRARED DETECTION AND CONTROLDEVICE BACKGROUND OF THE INVENTION The present invention relates to anelectronic detection and control device of the type adapted to beresponsive to the presence or absence of a physical object within aspecified area or responsive to any excessive ambient radiated energy.

This type of device has two broad areas of application. One such areamay be generally described as providing protection for machineoperators. In particular it is important from a safety point of viewthat the entire body of the operator be clear from a specified areaaround the machine during certain cycles of the machine. If for example,the machine were a power press, the operators hands must be removed fromthe die area of the press while the press is being actuated. To insurethat the operator takes this action, safety devices, such as mechanicalpull-back devices, have been provided. This type of device isessentially mechanical and is provided with handcuffs fitted about thewrists of the operator. The cuffs will automatically remove theoperators hands from the die area during press actuation. If theoperator should remove the cuffs from his wrists, the machine will bebypassed and continue to operate.

Other mechanical devices have been provided but are easily avoided bymerely disconnecting a linkage or other part. The motivation for takingsuch action might result from a piece-work scheme in which the operatorwishes to improve his speed believing that he can beat the machine.

Electronic devices have also been used for the protection of machineoperators. Photo-electric relays and other comparable devices have beenused to sense the interruption of a projected light beam. Theinterruption of the beams may be caused by the presence of a physicalobject, such as an operators hand. This type of device may be associatedwith systems for stopping the press in response to the presence of thephysical object. While these devices have gone part way in protectingthe operator, they may also be bypassed by means such as excessiveambient radiated energy. This energy may be accidentally or purposefullyintroduced to the sensing portion of the device to disrupt itsoperation. An infrared heater, sunlight, or a strobe light mayaccidentally cause such disruption of the device while an operatorsflashlight may purposefully be used to the same end.

The second broad area of application is the security area. The purposeof a device applied to this area would be to sense the presence of aforeign object within a defined area, such as an entrance to a bankvault. A secondary purpose might be to sense the presence of smoke orother types of clouding, such as a steam leak. The above-mentionedelectronic devices would be most pertinent to this area and have beenfound deficient for many of the same related reasons.

SUMMARY OF THE INVENTION It is, therefore, a primary object of thepresent invention to provide an electronic detection and control devicewhich is responsive to the presence or absence of any obstruction withina defined area, or responsive to the presence or absence within adefined area of any excessive ambient radiated energy.

provide an electronic detection and control device which will provide aprotective signal to an associated apparatus should any of the devicesimportant components or their associated circuits fail as a result of ashort or open or should the power source for the device fail.

It is still another object of this invention to provide an electronicdetection and control device which is operator proof and whose operationwill not be disrupted by excessive ambient radiated energy.

It is yet another object of this invention to provide an electronicdetection and control device which is adapted to sense the presence of aphysical object, such as smoke or steam.

It is still another object of this invention to provide an electronicdetection and control device comprising a first electronic circuit meanshaving its input connected to an electrical source, the output of saidfirst electronic circuit means connected to at least oneradiation-emitting semiconductor device, said first electronic circuitmeans adapted to provide electrical energy to said semiconductor deviceto excite said semiconductor device to produce a radiated signal, saidradiated signal defining an electronic screen, a radiation-sensingsemiconductor device whose input is adapted to receive said radiatedsignal, the output of said radiation-sensing semiconductor deviceconnected to a second circuit means, said second circuit means adaptedto provide an output signal responsive to the presence or absence of anyobstruction in said electronic screen, or responsive to the presence orabsence of any ambientradiated energy received by said radiation-sensingsemiconductor device.

It is yet another object of the present invention to provide aninexpensive, efficient, effective, compact electronic detection andcontrol device.

These and other objects of the invention, as well as the advantagesthereof over the prior art forms, will become apparent from thefollowing detailed descrip- DESCRIPTION OF THE DRAWINGS FIG. 1 is ageneral perspective view of one form of an electronic detection andcontrol device in accordance with the present invention; and

FIG. 2 is a block diagram showing the components in accordance with theinvention; and

FIG. 3 and 3A combined comprise a schematic wiring diagram of the systemof FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawing andparticularly to FIG. 1, there is therein shown one form of electronicdetection and control device which is adapted to be used in associatedwith a power apparatus such as a press (not shown).

The device 10 may comprise two columns 12 and 14 connected by a member)6. Column 14 is adapted to house and support an array of radiatingdiodes 18 which may be spaced on 2-inch centers. Column 12 is adapted tohouse and support an array of phototransistors 20, which may be spacedon l-inch centers.

The radiating diodes, such as infrared diodes 18, are excited with highcurrent pulses at a predetermined frequency in a manner to be laterexplained. The modulated infrared radiation signals emitted by thediodes 18 are thus detected by the array of phototransistors 20. Afterproper amplification, the signal is transmitted to the associatedcontrol circuitry in a manner to be later described. The circuitry issuitably housed in a compact fashion.

The control circuit constantly compares the received signal with thetransmitted signal emitted by the diodes l8. Whenever there is aphysical obstruction placed between the diodes l8 and phototransistors20, the received signal differs from the transmitted signal. Thissituation is detected by the circuitry, which develops a signal whichmay be used to control an associated apparatus, such as the press. Thecontrol could take the form of immediately braking the action of thepress by suitable means. Indication lights 22 may be provided toindicate an obstruction, and alarms and other warning devices (notshown) may also be suitably provided.

Additionally, the operation of the device 10 will not be disrupted tostray and excessive ambient infrared radiation. This ambient radiationmay he accidentally or purposefully caused. If, for example, should somecontent of stray radiation manage to fall on the phototransistors 20,the thus generated ambient signal will be compared by the circuitry, andthe resultant signal will be comparable to the obstruction signal andmay be used in the same manner to stop an apparatus, such as the actionof a power press. This activity may also be noted by a separateindication light 24.

The device 10 has been so provided to develop a substantiallyrectangular sensing curtain or screen, but it is obvious that it may bevaried depending on application (e.g., protective vs. security; type ofmachine; type of object being serviced, etc.).

Referring now to FIG. 2, there is therein shown a block diagram showingthe components in accordance with the present invention. An alternatingcurrent source 26 is connected to a power oscillator 28.

The A.C. source 26 is also connected to D.C. control power supply 30which will provide D.C. power for the associated electronic circuits. Anelectronic clock 32, which might typically be a commercially availableprogrammable unijunction transistor oscillator, is connected to thepower oscillator 28 to control the pulsing frequency of oscillator 28.The output of the oscillator 28 will excite the radiating diodes 34. Thediodes 34 may be set in an array of at least one diode and may betypically commercially available gallium arsenide diodes. The diodes 34will be so driven by the oscillator 28, whereby the emitted radiatedsignal will be in pulsed form. The pulsed signals will thereby form aradiation screen 36.

The clock 32 is also connected to a clock pulse stretcher 38, which maybe typically a commercially available one-shot multivibrator.

The pulse stretcher 38 transforms the clock pulse into a square wavesynchronizing pulse having a predetermined pulse-width time.

The radiation screen 36 passes through a filter 40, which may typicallybe a commercially available suitable glass or plastic material. Thefilter 40 filters radiation frequencies different from the band width ofthe radiation emission frequency of the radiating diodes 34. Theradiation screen 36 is then received by photodetectcr array 42. Thedetectors which may comprise the array 42 may be typically commerciallyavailable phototransistors.

The received signals are then amplified by an amplifier 44. Theamplifier is connected to a steering logic means 46 which steers theinformation signals received from the amplifier 44 to the respectivecircuits associated with the first and second coincidence detectioncircuits 54 and 60. An output signal of the steering logic means 46 ispassed through a first electrical noise" suppression circuit 50 whichwill allow the signal to proceed but will remove all unwantedinterference having a time duration less than that of the receivedsignal.

The first noise suppression circuit 50 is connected to the input of afirst obstruction pulse stretcher 52, which will transform the soreceived signal into a square wave pulse having a pulse-width timesubstantially equal to the transformed synchronizing pulse.

The transformed synchronizing pulse and the transformed received pulsewill then be electronically compared in a first coincidence circuit 54.The output signal of the first coincidence circuit 54 will remain at alogic value of zero so long as the synchronizing and received signalsare coincident with respect to time. If, however, there should be anyphysical obstruction in the radiation screen 36, then there would beinitially no signal received by that portion of the photodetector array42 in line with the obstruction. Therefore, there will be an absence ofa pulsed signal from the obstruction pulse stretcher 52. The outputsignal of the first coincidence circuit 54 will be then at a logic valueof. one so long as the synchronizing and received signal are notcoincident. It should be noted that it is the synchronizing signal thatremains constant and provides the measuring base, while the receivedsignal changes according to the presence or absence of an obstruction inthe radiation screen 36.

Another output of the steering logic means 46 is passed through a secondelectrical noise suppression circuit 56 which will allow the signal toproceed, but will remove all unwanted interference having a timeduration less than that of the received signal. The second noisesuppression circuit 56 is connected to the input of an ambient pulsestretcher 58, which will transform the so received signal into a squarewave pulse wave having a pulse-width time substantially equal to thetransformed synchronizing pulse.

The transformed synchronizing pulse and the transformed received pulsewill then be electronically compared in a second coincidence circuit 60.The output signal of the second coincidence circuit 60 will remain at alogic value of zero so long as the synchronizing and received signalsare coincident with respect to time. If however, there should be anyexcessive ambient radiated energy from a continuous or pulsed orintermitte rit source, as may be caused by sunlight, flashlight,infrared heater, or strobe-type light source received by thephotodetector array 42, photodetector array 42 will then be turned onaccordingly. That is, it will transmit an output signal having a waveform different than the wave form of the synchronizing signal. Thisdifference will then be detected by the second coincidence detectorcircuit 60. The output signal of the second coincidence circuit 60 willbe then at a logic value of one so long as the synchronizing andreceived signal lack coincidence. It should also be here noted that isthe synchronizing signal that remains constant and provides themeasuring base, while the received signal changes according to thepresence or absence of excessive ambient radiated energy introduced intothe radiation screen 36.

It should also be noted that by so providing an electronic detection andcontrol device, as depicted in FIGS. 1, 2 and 3, which will be laterexplained, the first coincidence electronic circuit 54 and the secondcoincidence circuit 60 will also transmit a signal in response to shortor open condition in any important part of the device as well as anyfailure of the A.C. source 26. This means that upon occurrence of any ofthe above-mentioned failures, a signal would be generated to immediatelycontrol an apparatus such as a power press.

Now referring to FIG. 3, there is therein shown a specific circuit 62for controlling a typical power press (not shown) embodying the conceptsof the present invention, and having input terminals 64 and 66, andground terminal 68. lnput line voltage is a typical application for 117Vac signal phase. Switch 70 contact is switched to apply line power to alight 72, to a stepdown transformer 74, to a silicon diode rectifierbridge 76 comprising silicon diodes 78, which might typically rectifythe A.C. input to obtain a D.C. voltage across capacitor 80. Resistor 82limits the peak currents flowing into capacitor 80 at typically a 120Hertz rate. Capacitor 84 is also charged to the same value and polarityof voltage as capacitor 80 through resistor 86.

Logic means 88 is used to turn on SCR 90 by a single pulsed gate signalat a fixed repetition rate. This will allow a pulse of current to flowfrom capacitor 84, through reactor 92, SCR 90, resistor 94, infrareddiodes 96 and then back to capacitor 84. This current will resonantlyreverse the polarity on capacitor 84 and reduce to a zero value. Thenthe current will reverse its flow from capacitor 84, through diode 98,resistor 100, diode 102, reactor 92, and back to capacitor 84. This willreverse the polarity of the voltage across SCR 90 during the same timeinterval that the forward current is zero value through SCR 90.Therefore, SCR 90 will recover its forward blocking state. This currentwill also resonantly return the voltage across capacitor 84 to itsoriginal polarity and conditions are ready to repeat another cycle. Theobject of this repeating function is to pass pulses of current throughthe infrared diode 86, which will emit infrared radiation signals whenthey are so excited. Since the infrared diodes 96 are all pulsed at thesame time, and therefore, emit infrared radiation at the same time, theyform a curtain or screen 104 of radiation formed at a predeterminedrepetition rate.

The clock or logic means 88, which is used to determine the repetitionrate, might typically be a relaxation oscillator using a programmableunijunction transistor 106; and resistors 108, 110, 112, 114 andcapacitor 116. This circuit delivers the gate pulse current to SCRthrough resistor 118 to initiate the transmitted signal. This clockpulse is amplified by transistor 120 and is also transformed into asquare wave synchronizing pulse having a predetermined pulse width time,by a typical one-shot oscillator pulse stretcher 122 using transistors124, 126; resistors 128, 130, 132, 134; pot 136; and capacitor 138. Thetransmitted signals are received by the array of phototransistors 140.The received signals are then amplified respectively by transistors 142and then inverted respectively by transistors 144. The signals at thispoint are all paralleled and passed through a noise suppression circuit146 using a programmable unijunction transistor 148, which will allowthe signal to pass through, but will not pass unwanted interferencehaving a time duration less than that of the received signal. Thisreceived signal, that is passed through, will oncshot turn on transistor150, which will activate a one-shot pulse stretcher 142 152 transistors154 and 156; and resistors 158, 160, 162, 164; pot 166; diode 168; andcapacitor 170, which will transform the received signal into a squarewave pulse having a pulse width time approximately equal to that of thetransformed synchronizing pulse.

The transformed synchronizing pulse and the transformed received pulsewill now be compared in coincidence detection circuit 172, which willfunction in the following manner: When the base of transistor 174receives a logic 1 signal, its collector output signal will be at logic0" state. Conversely, when there is a 0 signal at the base of transistor174, its collector output signal will be a l. Transistor 176 performs ina like manner. Therefore, if the received and the synchronizing signalsare both 1, the outputs of transistor 174 and 176 will be 0. The basesignal of the transistor 180 will be 1 through diode 182 and resistor184; therefore, the collector output signal of transistor 180 will be 0.Likewise, if the received and synchronizing signals are both 0," theoutputs of transistor 174 and transistor 176 will be l, the base signalof transistor 178 will be l and the collector of transistor 178 will be0. However, the base signal of transistor 180 will still be 1" throughdiode 186 and resistor 188; therefore, the collector output signal oftransistor 180 will still be 0. Thus, the output of transistor 180 willremain at 0 as long as the synchronizing and received signals arecoincident with respect to time.

If an obstruction should appear in the screen 104, then one or more ofthe obstructed phototransistors will notreceive a transmitted signal.There would then be a 0" signal on the base of the associated transistor142 and the collector of the so effected transistor 142 would be a l."The base signal would be a l on associated transistor 144 and itscollector output signal would be a 0. (This will be true even though theother signals are received.) Therefore, the base signal of transistor150 will be a and its collector and the base signal of transistor 174will be a l. The collector of transistor 154 remains at 0" during theperiod of obstruction, thereby stopping the supply of energizing pulsesto the relay coil 220 causing it to deenergize. At the same time, whenthe collector signal of transistor 150 goes to 0, the collector signalof transistor 174 will also be at 0. In this same time interval, thesynchronizing signal will appear as a 1 on the base of transistor 120causing a 0 on the collector of transistor 120, transforming thesynchronizing pulse into a square wave signal of a 0 on the base oftransistor 176, and a l on the collector of transistor 176. This willappear as a 1" signal on the base of transistor 178 through diode 190,giving a 0 signal on the collector of transistor 178 and the base oftransistor 180. From above, since there will be a 0 signal on thecollector of transistor 174, the current will flow through diode 192 toground, leaving a 0 signal on the base of transistor 180. Since bothinput signals to the base of transistor 180 are 0, there will be a 1"signal on the collector of transistor 180, which will allow the noisesuppressor (including sensitivity adjustment) and pulse generatorcircuit 194 using capacitor 196; resistors 198, 200, 202; andprogrammable unijunction transistor 204 to generate a gate pulse ofcurrent through resistor 206, the gate of SCR 208 and through the powerpress foot switch reset contacts 210, which are normally open, but wouldbe closed during press operation. A parallel path will also deliver agate pulse of current through resistor 212, diode 214, the gate of SCR216, and through the foot switch reset contacts 210. The turn-on of SCR208 would light the obstruction indication light 218 and the turn-on ofSCR 216 ensures that the current remains shunted away from the relaycoil 220 causing it to remain deenergized even though the obstruction isremoved. The punch press will not operate until the relay coil 220 andits associated circuitry has been reset by the operator through the footswitch contacts 210.

An additional important feature of this device is that it is capable ofdetecting radiated energy from a continuous pulsed or intermittentsource as may be introduced within the screen 104. This may occuraccidentally as by an infrared heater or strobe-type energy source, orpurposefully as by a flashlight. This is achieved by the followingmeans: The collector output signals of transistors 142 are monitoredthrough diodes 222. These signals are then paralleled, inverted bytransistor 224, noise suppressed by programmable unijunction transistor226, transformed by pulse stretcher 228, using transistors 230 and 232,and compared for coincidence by the coincidence detection circuit 234,with the synchronizing signal by transistors 176, 236, 238 and 240. Aslong as excessive ambient radiation is not received by any one of thephototransistors, there will be a 0 output signal at the collector oftransistor 240. Should any of the collector signals of transistor 142 bealways 0" due to excessive ambient, the ambient detection circuit andthe coincidence detection circuit 234 will cause the output signal atthe collector of transistor 240 to be 13* (The operation of thesecircuits is similar to the operation of the obstruction detectioncircuit and the coincidence detection circuit 172). The l output signalfrom the collector of transistor 240 will turn on programmableunijunction transistor 242 (which will operate similar to thedescription of the operation of noise suppression and pulse generatorcircuit 194 using programmable unijunction transistor 204), which willdeliver a gate pulse to SCR 244, which will turn on SCR 244, which willturn on the excessive ambient radiation indication light 246, and in thesame time interval in a parallel path, the pulse generator 242 willdeliver a gate pulse to SCR 216, which will turn on SCR 216, which willshunt current away from the relay coil 220, which will cause relay coil220 to deenergize, which will, in manner as before described, stop theoperation of the press.

The DC. power for the control circuits might typically be derived fromthe circuit 248, which consists of a step-down transformer 76, a DC.bridge rectifier 250, filter capacitor 252, filter capacitor 254, filterresistors 256, 258, and zener reference diode 260.

An additional important feature is to provide a circuit which willgenerate a signal in response to a short or open condition in itsimportant components or associated circuitry as well as in response toany failure to the power supply. This signal could also be used tooperate a relay to control the operation of a power press.

An example of a short condition detection can be illustrated iftransistor 154 should for some reason fail short. This malfunction willdeenergize the output relay coil 220. This will stop the operation ofthe press because the relay coil 220 is energized through the sameresistor 162 that is used in the pulse stretcher circuit 152.Accordingly, this failure will have the same result in terms ofoperating the relay as would occur if there was an obstruction in thescreen 104.

Although the above embodiments have been directed to the use of discretecomponents, it should be understood that other circuit technology couldbe employed within the scope of the invention. That is, integratedcircuits and other similar circuit technology could be used to providean electronic detection and control device in accordance with thisinvention.

While certain specific embodiments have been alluded to for the purposeof illustration, it is to be understood that the present invention canbe applied to various uses and adaptations that may be made therein, aswill be apparent to a person skilled in the art.

We claim:

1. An electronic detection and control device comprising a firstelectronic circuit means having its input connected to an electricalsource, the output of said first electronic circuit means connected toat least one radiation-emitting semiconductor device, said firstelectronic circuit means adapted to provide electrical energy to saidsemiconductor device to excite said semiconductor device to produce aradiated signal, said radiated signal defining a radiating screen, aradiation sensing semiconductor device whose input is adapted to receivesaid radiated signal, the output of said radiation sensing semiconductordevice connected to a second circuit means, said second circuit meansadapted to provide an output signal-responsive to the presence ofabsence of any obstruction in said electronic screen, or responsive tothe presence or absence of any ambient radiated energy received by saidradiation sensing semiconductor device, said first circuit means isadapted to provide an output signal responsive to an open or shortcondition in any of the components or circuits of said device andresponsive to any failure of said electrical source.

2. An electronic detection and control device in accordance with claim 1wherein said first circuit means is further provided with electronictiming means whose output signal controls the timing of the output ofthe first electronic circuit means.

3. An electronic detection and control device in accordance with claim 2wherein said second circuit means is further provided with means toamplify the output signal of said radiation-sensing semiconductor deviceand means to then steer and invert the thus amplified signal and meansto then suppress stray electrical signals and means to then increase theduration of the signal, said electronic timing means further providingan output signal which is increased in duration by a third electroniccircuit means, a fourth circuit means to electronicallycompare the timecoincidence of the output signals of said second circuit means with theoutput signal of said third circuit means, whereby said fourth circuitmeans will provide an output signal responsive to whether or not saidoutput signals of said second and third circuit means are coincidentwith respect to time.

4. An electronic detection and control device in accordance with claim 3wherein said first electronic circuit means is an oscillator.

5. An electronic detection and control device in accordance with claim 4wherein said oscillator is in series with said radiation-emittingsemiconductor device, and wherein said radiation-emitting semiconductordevice is an infrared diode.

6. An electronic detection and control device in accordance with claim 3wherein the output signal of said fourth circuit means will control thecontrol device of an associated apparatus.

1. An electronic detection and control device comprising a first electronic circuit means having its input connected to an electrical source, the output of said first electronic circuit means connected to at least one radiation-emitting semiconductor device, said first electronic circuit means adapted to provide electrical energy to said semiconductor device to excite said semiconductor device to produce a radiated signal, said radiated signal defining a radiating screen, a radiation sensing semiconductor device whose input is adapted to receive said radiated signal, the output of said radiation sensing semiconductor device connected to a second circuit means, said second circuit means adapted to provide an output signal responsive to the presence of absence of any obstruction in said electronic screen, or responsive to the presence or absence of any ambient radiated energy received by said radiation sensing semiconductor device, said first circuit means is adapted to provide an output signal responsive to an open or short condition in any of the components or circuits of said device and responsive to any failure of said electrical source.
 2. An electronic detection and control device in accordance with claim 1 wherein said first circuit means is further provided with electronic timing means whose output signal controls the timing of the output of the first electronic circuit means.
 3. An electronic detection and control device in accordance with claim 2 wherein said second circuit means is further provided with means to amplify the output signal of said radiation-sensing semiconductor device and means to then steer and invert the thus amplified signal and means to then suppress stray electrical signals and means to then increase the duration of the signal, said electronic timing means further providing an output signal which is increased in duration by a third electronic circuit means, a fourth circuit means to electronically compare the time coincidence of the output signals of said second circuit means with the output signal of said third circuit means, whereby said fourth circuit means will provide an output signal responsive to whether or not said output signals of said second and third circuit means are coincident with respect to time.
 4. An electronic detection and control device in accordance with claim 3 wherein said first electronic circuit means is an oscillator.
 5. An electronic detection and control device in accordance with claim 4 wherein said oscillator is in series with said radiation-emitting semiconductor device, and wherein said radiation-emitting semiconductor device is an infrared diode.
 6. An electronic detection and control device in accordance with claim 3 wherein the output signal of said fourth circuit means will control the control device of an associated apparatus. 